Nistune Forums

I've spent already two days but haven't found the problem on an EDM S13 200sx CA18det. Firstly I just done a initial map.
Every time i try to rev the car @ WOT up, it shouds down the injection between 4000-5000rpm. The engine struggels than and runs only on idle for about 30seconds until it goes back to normal oparation (until you rev it once again over 4000rpm). When the car has been could for a while i can rev the engine 2-3 times over 5000rpm without problems.

I already tried and changed the follow things

- Airflowmeter
- ECU which is tune for a similary setup > same problem
- CAS Sensor
- Ignition modul
- disconnectet Knock Sensor (which is not attached to the engine block, because ther sits the external knock device to do the mapping)
- disconnect Std. boost valve
- measured the injector harness out. seams to be okay.


You can clearly see in the datalog that the injection shouts down. I think it could be a mechanical issue that turns ECU in a "safety modus" or somthing else.

Does anybody know if there is a safety future or somthing else in the ECU that can cause this reaction? Or had had somebody similary issues?
Thanks for effery tip!

Sounds like the problems run deeper than this, but were you aware that CA18's switch from sequential to batch fire when they come on boost? At which point injection time halves.

Pete L

That is what is going on... once injection time hits about 7.5ms the injection time halves and switches sequential to batch which is what you are seeing in the logs. What does the AFR look like in comparison?

Yes I know that. You can clearly see that it change the injection method before the injection shouts down. It looks like the first action is that the ECU shout down the injectors and in consequence the MAF signal goes down. After that the injection time doesnt' go about 2-3 ms no matter how much you stay on the throttle.
I'm not sure about the using of the TTP Tables. I think they fuction a bit different to other ECU's.

- TPPMin shows the minimum injection time to change injection mehtode to batchfire
- TPPMax shows as usual max injection time.
- TPPMax 2 shows??

Can someone explain that?


Hower I don't think that the problem is caused from wrong ECU calibraition. Because we tried an ECU wich is proved to run with a similary setup. > same Problem

I changed the injectors to std. RB26det 444cc and the AFM to a Z32 before I started with tuning. Unfortunately the owner don't know if the problem was also before the change of this componets, because he only drove the car into my garage and never reved it above 4000rpm since he has rebuilt it. I already changed the Z32 MAF with one that is proven to run and rechecked the wiring.

What happens if the CAS looses the signal in high rpm's on the CA18det? I don't know for sure that the spare CAS wich I tried is working correctly. Other engines begins to poop an bang on high rpms when there is a CAS fault and don't shout down the injection.

Thanks for your help!

Put the log and BIN file up here or email it to me (info @nistune.com) directly and I'll run it on the bench tomorrow when I get time. I've got a few others to look at and working stupid hours today to keep up with support work so may be some time before I get to it

Sent you a mail. Thank you for your efforts!

Matt wrote:Put the log and BIN file up here or email it to me (info @nistune.com) directly and I'll run it on the bench tomorrow when I get time. I've got a few others to look at and working stupid hours today to keep up with support work so may be some time before I get to it

TTPmin is different on CA18 compared to other vehicles. The value used must be divided by 16 to get the minimum TP index

TTP min specifies the minimum TP value which the ECU will use at the specified RPM.

TTPmin =
144 – 154 => lowest TP = 2304 (idx = 9)
128 – 143 => lowest TP = 2048 (idx =
112 – 127 => lowest TP = 1792 (idx = 7)
96 – 111 => lowest TP = 1536 (idx = 6)
80 – 95 => lowest TP = 1280 (idx = 5)

Yours has changed:
179 179 179 179 179 154 154 154 (Minimum TP index 11 .. 9)
120 120 120 120 120 103 103 103 (Minimum TP index 7 .. 6)

Which allows a lower pulsewdith. This will not affect the change between sequential/batch which is a fixed injection time

TTPmax is same as other ECUs. TTPMax2 is another table I found near these two in the code but I have not seen the need to change it yet.

Nissan CAS faults tend to either make the engine not start or perhaps run intermittently at top end. You will get a CAS DTC if it skips a beat